This invention relates to current distribution devices and, more particularly, to molded commutator assemblies in which the coil ends are secured to commutator segments disposed about a molded core.
A conventional commutator assembly normally includes a core of insulating material having a plurality of commutator segments disposed around the core and extending longitudinally thereof. Some form of locating or securing means are provided at one end of the commutator segments for receiving and holding the coil ends of an appropriate motor armature in engagement with respective ones of the commutator segments. The coil ends must be accurately and effectively located to achieve and insure the shortest possible welding or brazing cycles in permanently connecting the coil ends to the commutator segments. Although welding is a common term, the coil ends actually are fused to the commutator segments. The fusing is somewhat akin to resistance welding but more on the order of hot staking.
For instance, some commutator assemblies have segments anchored in the molded core of the assembly. The segments are fabricated from relatively thin sheet material, such as copper, and one end of each segment is provided with a bent hook element for receiving and holding a coil end for subsequent welding or brazing. In somewhat larger commutator assemblies, each commutator segment is individually formed as a bar-like element. A composite riser means is formed at one end of the commutator, including a riser portion for each commutator bar. The riser portion has a slot formed therein for receiving and holding a coil end. Actually, the slot would normally receive plural or positive and negative wires. The risers are formed by machining down the commutator bars to form radially extending flanges at one end of the commutator, the flanges being provided with the slots for receiving the coil ends. The commutator bars are fabricated of appropriate material, such as copper.
Obvious problems are inherent in fabricating commutator assemblies of the latter type described above which include commutator bars having integral, slotted risers. For instance, there is a considerable waste of copper material in machining the bars down to form the slotted flanges. An additional fabricating step is required in forming the slots themselves. Furthermore, since the slots must be slightly narrower than the coil ends, it is somewhat difficult to position the coil ends into the slots in any efficient manner. Guide means may be formed on the risers about the slots, but this would require still additional fabricating steps.
Some commutator assemblies have commutator bars or segments formed with integral hooks at their ends for anchoring the coil ends or wires. Some of the same inherent problems described above are present with such assemblies.
This invention is directed to solving the above problems by providing a commutator assembly which includes riser means molded independently of the commutator segments for receiving and holding the coil ends.